CLASSIFICATION AND THE PREDICABLES. 95 



orders, Plantigrades, Digitigrades, etc., are as much the expression of at- 

 tributes as if those names had preceded, instead of grown out of, his clas- 

 sitication of animals. The only peculiarity of the case is, that the conven- 

 ience of classification was here the primary motive for introducing the 

 names ; while in other cases the name is introduced as a means of predica- 

 tion, and the formation of a class denoted by it is only an indirect conse- 

 quence. 



The principles which ought to regulate Classification, as a logical process 

 subservient to the investigation of truth, can not be discussed to any pur- 

 pose until a much later stage of our inquiry. But, of Classification as re- 

 sulting from, and implied in, the fact of employing general language, we 

 can not forbear to treat here, without leaving the theory of general names, 

 and of their employment in predication, mutilated and formless. 



§ 2. This portion of the theory of general language is the subject of 

 what is termed the doctrine of the Predicables ; a set of distinctions hand- 

 ed down from Aristotle, and his follower Porphyry, many of which have 

 taken a firm root in scientific, and some of them even in popular, phraseolo- 

 gy. The predicables are a fivefold division of General Names, not ground- 

 ed as usual on a difference in their meaning, that is, in the attribute which 

 they connote, but on a difference in the kind of class which they denote. 

 We may predicate of a thing five different varieties of class-name : 



A genus of the thing {ykvoo). 



A species {tlloo). 



A differentia {ha^opa). 



A proprium {^iZiov). 



An accide7is {(xv^fitfiriKoo). 



It is to be remarked of these distinctions, that they express, not what the 

 predicate is in its own meaning, but what relation it bears to the subject 

 of which it happens on the particular occasion to be predicated. There 

 are not some names which are exclusively genera, and others Avhich are ex- 

 clusively species, or differentiae ; but the same name is referred to one or 

 another predicable, according to the subject of which it is predicated on 

 the particular occasion. Animal, for instance, is a genus Avith respect to 

 man, or John ; a species with respect to Substance, or Being. Rectangu- 

 lar is one of the Differentiae of a geometrical square; it is merely one of 

 the Accidentia of the table at Avhich I am writing. The words genus, spe- 

 cies, etc., are therefore relative terms ; they are names applied to certain 

 predicates, to express the relation between them and some given subject : a 

 relation grounded, as we shall see, not on what the predicate connotes, but 

 on the class which it denotes, and on the place which, in some given classi- 

 fication, that class occupies relatively to the particular subject. 



§ 3. Of these five names, two. Genus and Species, are not only used by 

 naturalists in a technical acceptation not precisely agreeing with their phil- 

 osophical meaning, but have also acquired a popular acceptation, much 

 more general than either. In this popular sense any two classes, one of 

 which includes the whole of the other and more, may be called a Genus 

 and a Species. Such, for instance, are Animal and Man ; Man and Mathe- 

 matician. Animal is a Genus; Man and Brute are its two species; or we 

 may divide it into a greater number of species, as man, horse, dog, etc. 

 Biped, or two-footed animal, may also be considered a genus, of which 



